The next year, he was 10-8 with a 3.84 ERA in 26 starts for the Dayton Dragons. He began 2008 with the Sarasota Reds and went 7-2 with a 2.55 ERA in 10 starts before being promoted to the Chattanooga Lookouts in May. He was 2-6 with a 5.40 ERA in 11 starts that year for the Lookouts. He remained at the AA level with the Carolina Mudcats in 2009, going 5-3 with a 3.44 ERA in 13 starts while battling right elbow and left knee injuries.

Back with Carolina to begin the 2010 campaign, Smith was 1-3 with a 5.08 ERA in 27 appearances out of the bullpen. On June 15th, he was recalled by the Reds, and he made his debut that day, throwing a scoreless inning of relief against the Los Angeles Dodgers.